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Invasive bee species may have a widely detrimental impact on their novel host ecosystem. Introduced bees can rapidly disrupt native plant-pollinator mutualisms through competition with indigenous pollinator fauna and facilitation of invasive flora reproduction. Island ecosystems, which are inherently limited in physical range, resource availability, and trophic diversity, tend to be particularly sensitive to ecological impacts of invasive species. The small green carpenter bee Ceratina (Pithitis) smaragdula occurs throughout Southeast Asia and across the Hawaiian archipelago. Historical records indicate that C. smaragdula is nonnative to the Hawaiian archipelago and is recently introduced. Here we present a comprehensive synthesis of C. smaragdula's known biological and ecological history, as well as a population genetic analysis of C. smaragdula from Maui, and from locations across its native range, at the cytochrome oxidase I (COI) locus. We update C. smaragdula's known distribution and occurrence elevation in Hawai‘i and reveal a lack of genetic structure between Hawaiian and native range populations. We discuss points of origin, means of introduction, and potential ecological impact of this nonnative pollinator.
Human alterations of coastal wetlands in Hawai‘i began when Polynesians first colonized the Hawaiian Islands more than 1,000 yr ago. There are contrasting hypotheses and results in studies on impact of anthropogenic forcings on Hawaiian coastal wetland ecosystems. Here we report results of a multibiogeochemical proxy investigation of sedimentary carbon and nitrogen dynamics of a coastal wetland, Kawainui Marsh, on the island of O‘ahu, Hawai‘i. Our results show that humans have impacted Kawainui Marsh in two main ways, upland “indirect” impact and wetland “direct” influence. The former, characterized by decreased δ13C and increased δ15N of sedimentary organic matter (SOM) and elevated concentrations of long-chain n-alkanes, reflects human land-use change in the upland areas of the marsh: cultivation and grazing. The latter, peaking between A.D. 1690 and 1750, is characterized by sharply increased sedimentation rate and mass accumulation rate of SOM, decreased δ13C and δ15N, and elevated C/N and total organic carbon (TOC). These results indicate the direct influence of human impact: the Polynesian transformation and utilization of the ponded (open water) area of the marsh into fishponds. This is the first biogeochemical investigation conducted in the marsh. Our results provide valuable new insights into the history of the pre- and post-European human impact on the marsh.
In this study we present a first limnological characterization of Lake Billy Mitchell [1,013 m above sea level (a.s.l.), 88.3 m depth, 3 km2 surface area] in central Bougainville Island, Papua New Guinea. Physicochemical depth profiles indicated mixis of the entire water body with oxygen saturation reaching 55% in the deepest layers. A shallow thermocline was eroded at night, indicating atelomixis. , Cl−, and Na, Ca2 , Mg2 were the dominant anions and cations, respectively, leading to a conductivity of around 1,230 µS cm−1. The pH was close to neutral throughout the water column, and no accumulation of CO2 was observed at greater depths. With a total phosphorus concentration of around 25 µg liter-1 the lake can be considered as meso- to eutrophic. The phytoplankton community consisted of 18 taxa. The dinophyte Peridiniopsis cf. penardii and the filamentous green alga Planctonema lauterbornii dominated in the uppermost layer and reached a total biovolume around 16 mm3 liter-1. Six macrophyte taxa were found (three Spermatophyta/three Bryophyta), with the water chestnut Eleocharis dulcis covering the shoreline and Ceratophyllum demersum spreading to at least 3 m depth. Seven ciliate species were detected (<5 individuals ml-1) with bacterivorous scuticociliates and the prostomatid Coleps hirtus hirtus dominating the assemblage. The micrometazoan plankton community comprised the rotifer Anuraeopsis fissa, the copepod Mesocyclops cf. affinis, and a cladoceran species within the Ceriodaphnia cornuta group all concentrating in the upper water column. The only fish species found in the lake was the eel Anguilla megastoma, whereas in the effluent river this species occurred together with Anguilla marmorata.
Understanding microhabitat use of an organism is an important first step to understanding its ecology and also provides critical information for guiding management and conservation efforts. Most microhabitat studies of freshwater fishes have focused on temperate systems, with far less research on fish microhabitat use in tropical streams. Here, we studied microhabitat use and selectivity patterns of juvenile Mugil cephalus within a Hawaiian stream, USA (Waiāhole Stream, latitude: 21.48°, longitude: -157.85°). We measured depth, velocity, substrate composition, and canopy cover at locations where M. cephalus was observed feeding and compared attributes of these locations to microhabitat available to the fish. We found significant differences in microhabitats where mullet fed compared to microhabitats available, with feeding occurring in microhabitats with moderate velocities (0.21–0.60 m/sec), shallow to moderate depths (0.31–0.80 m), gravel and pebble as dominant substrates, and low canopy cover. Results of our study suggest that juvenile M. cephalus are selecting erosional habitats and avoiding depositional habitats, a result that was also supported by a multivariate analysis of habitat selectivity. Our data corroborate results of other studies reporting that fish grazers select habitats that are clean (erosional) rather than silted (depositional). Knowing how M. cephalus in streams use the available habitats is important for understanding how to manage freshwater habitat to support juvenile M. cephalus in the face of increasing anthropogenic impacts and a changing climate.
Diet of the volcano keyhole limpet Fissurella volcano was determined from stomach contents of 56 specimens collected from two rocky reefs along the west coast of the Baja California Peninsula of Mexico in July and November 2006 and March 2007. We identified 40 taxa, including 27 diatoms, one cyanoprokaryota, eight macroalgae (mainly red algae), one sea grass, and three protozoans. Food items >20% in relative frequency were diatoms, cyanoprokaryota, and Pyropia sp. Among the diatoms, 10 species represent 80% of relative frequency (Grammatophora marina, Cocconeis speciosa, Navicula longa, Amphora sp., Cocconeis dirupta, Tabularia investiens, Cocconeis plancentula, Cocconeis distans, Tabulariafasciculata, and Cocconeis notata). These findings suggest that Fissurella volcano is a herbivore with preference for diatoms, periphyton, and foliose and filamentous red seaweeds.
Moku‘ae‘ae Rock Islet is located off the north shore of Kaua‘i and is protected as a Hawai‘i State Seabird Sanctuary. In the late 1970s it was also the site of a cross-fostering project for the endangered Newell's Shearwater, Puffinus newelli. Few avifauna surveys have been undertaken on the islet, and none since 2007. In 2013 and 2015, we conducted burrow searches across the entire islet to obtain breeding population estimates for each species and to evaluate whether the Newell's Shearwater had become established as a breeding species after the cross-fostering project. Auditory surveys were also conducted for 2 hr after sunset and 1.5 hr before sunrise, which are the peak calling periods for the Newell's Shearwater on Kaua‘i. A total of seven seabird species was recorded on the islet, of which three, Bulwer’s Petrel, Bulweria bulwerii; Wedge-tailed Shearwater, Ardenna pacifica; and Red-tailed Tropicbird, Phaethon rubricauda, were confirmed breeding. This is the first time Bulwer's Petrel has been confirmed breeding on Moku‘ae‘ae. Searches for Newell's Shearwater did not produce evidence that this species breeds on the islet, suggesting that the cross-fostering project was not successful. Although the islet is small, it represents an important refuge for seabird species. However, high levels of depredation were recorded on Bulwer's Petrel; we conclude that these were all killed by the introduced Barn Owl, Tyto alba, based on disposition of the bodies and the injuries they had sustained. Management recommendations for the islet include creation of a management plan, annual breeding bird surveys, annual rat monitoring, and Barn Owl control.
A new species of Crypthelia, C. kelleyi, is described from a seamount in the Northwestern Hawaiian Islands, making it the fifth species of stylasterid known from the Hawaiian Islands. Collected at 2,116 m, it is the fourth-deepest stylasterid species known.
New locality records are given for 10 species of butterflies from 10 islands and island groups (atolls) within the Federated States of Micronesia (FSM). All the species recorded are widespread in the Pacific and in many cases farther afield. We report the first record of Badamia exclamationis from Kosrae (the second for the FSM) and the first record of Catopsilia pomona from Chuuk State. Danaus plexippus is intermittently distributed in the FSM but often observed where the introduced ornamental Calotropis gigantea is common. Hypolimnasbolina was one of the most frequently encountered species during this study. The extent of variation in coloration and pattern within local populations of H. bolina in the FSM and adjacent areas of Oceania suggests that use of sub-species names is probably unwarranted.
Ten species of Cyrtodactylus from Southeast Asia were examined for gastrointestinal helminths. Samples consisted of eight species from Malaysia: Cyrtodactylus aurensis, Cyrtodactylus australotitiwangsaensis, Cyrtodactylus batucolus, Cyrtodactylus consobrinus, Cyrtodactylus ingeri, Cyrtodactylus macrotuberculatus, Cyrtodactylus semenanjungensis, and Cyrtodactylus tiomanensis; and two species from Vietnam: Cyrtodactylus condorensis and Cyrtodactylus huynhi. The helminth community consisted of one species of Cestoda, Oochoristica javaensis, and eight species of Nematoda: Bakeria schadi, Cosmocerca ornata, Parapharyngodon maplestoni, Physalopteroides dactyluris, Spauligodon bintangensis, Abbreviata sp. (larvae), Ascarididae gen. sp. (larvae), and Physalopteridae gen. sp. (larvae). Parapharyngodon maplestoni had the largest number of individuals and the greatest prevalence (100% in each of C. aurensis and C. ingeri). Twenty-one new host records are reported.